Sensory factors which affect the acceptance of raw and heated defatted soybeans by rats

The acceptability of heated soybean meal (HS) compared to raw soybean flakes (RS) was studied by means of diet selection in free choice situations. The selection by rats of diets containing HS over those containing RS was shown in short- and long-term preference tests. Texture did not seem to be an important factor in the acceptability difference between HS and RS. Rats selected a less nutritious diet containing RS + sodium saccharin (appealing taste) over a diet containing HS + sucrose octaacetate (aversive taste) for an initial 6 to 7 days, suggesting that post-ingestional factors did not markedly affect the acceptability during that period. However, after this initial period, the rats selected the diet of higher nutritive value, even though it had added sucrose octaacetate. Preference tests before and after producing anosmia indicated that RS contains an aversive odor(s) which could be removed by vacuum treatment. Heated soybean meal was found to contain an appealing taste stimulus (i) which could also be removed by vacuum treatment.